In FDD communication, different frequencies are used in transmission and reception. For this reason, a radio communication apparatus needs a transmission antenna and a transmission filter which passes a transmission frequency band, and a reception antenna and a reception filter which passes a reception frequency band.
If MIMO, in which plural radio transmission channels and plural radio reception channels are used simultaneously and in parallel, is applied in FDD, the communication apparatus needs the transmission antennas and the transmission filters which pass the transmission frequency band equal to the number of the transmission channels, and the reception antennas and the reception filters which pass the reception frequency band equal to the number of the reception channels.
Therefore, increase of the transmission channels and the reception channels in order to accelerate communication speed requires the antennas and the filters equal to the increased number of the channels. As a result, there is a problem that circuit area for installation of the antennas and the filters increases.
To cope with the problem, for instance, a technique disclosed in Patent Document 1 may be applied. Patent Document 1 discloses a multiband radio communication apparatus that includes plural antennas, plural filters, plural duplexers, a modulation circuit, and a demodulation circuit. Because a duplexer is connected to a transmission circuit and a reception circuit is connected to one antenna, the apparatus is able to execute both transmission and reception using the one antenna. In the above-mentioned manner, the number of the antennas can be reduced.